In studying altered gene expression in mouse hepatomas, the level of seven enzymes that we have examined demonstrate a correlation between fetal liver and hepatomas, having either decreased or increased activity when compared to normal adult liver. Two enzymes, glucose-6-phosphate and 6-phosphogluconate dehydrogenases, are increased in fetal liver and hepatoma, while NAD-malate dehydrogenase, aspartate aminotransferase, alcohol dehydrogenase and NADP-isocitrate dehydrogenase are decreased in activity in fetal liver and hepatoma, all relative to adult liver. Glucose phosphate isomerase has little developmental change in activity and exhibits no change in activity between hepatoma and adult liver. The objective of this study is to determine whether the deviation in the hepatoma from normal liver and its fetal-like gene expression is due to an alteration in the rate of enzyme synthesis or degradation. Four of these enzymes have already been purified and antibodies to these enzymes have been prepared. To measure turnover of these enzymes, radiolabeling and specific immunoprecipitation techniques will be used. In addition, a cell free translation system will be employed to measure amounts of messenger RNA present in hepatoma and liver. The effects of various dietary regimes upon enzymes level in liver and hepatoma will also be investigated.